Fluids flow system with self-flushing revolving filter

ABSTRACT

Pumps or other fluids handling devices are protected from contaminants in the fluids by alternately presenting localized portions of a filter media to the flow paths of fluids entering and leaving the device to filter out the contaminants from the fluids entering the device and to flush out the filter media with the fluids leaving the device. In a preferred embodiment, a continuous revolving filter intersects the inlet and discharge passages of a pump to divert contaminant particles in the fluid from the pump inlet to the pump outlet without allowing the particles to pass through the pump, and concurrently backwashing the filter element by pressurized fluid from the pump.

United States Patent Grill 51 May 23, 1972 FLUIDS FLOW SYSTEM WITH SELF-FLUSHING REVOLVING FILTER [72] Inventor: Raymond J. Grill, RichmondHeights,

Ohio

[73] Assignee: TRW Inc., Cleveland, Ohio [22] Filed: Nov. 4, 1969 [21]App]. No.: 873,970

[52] U.S.Cl ..2l0/391,210/416 [51] Int. Cl 1 ..B0ld 33/22 [58]FieldofSearch ..210/39l,393,416

[56] References Cited UNITED STATES PATENTS 2,266,980 12/1941 McNeal..210/393 Primary ExaminerJ. L. De Cesare Att0rney-Hill, Sherman,Meroni, Gross & Simpson ABSTRACT Pumps or other fluids handling devicesare protected from contaminants in the fluids by alternately presentinglocalized portions of a filter media to the flow paths of fluidsentering and leaving the device to filter out the contaminants from thefluids entering the device and to flush out the filter media with thefluids leaving the device. In a preferred embodiment, a continuousrevolving filter intersects the inlet and discharge passages of a pumpto divert contaminant particles in the fluid from the pump inlet to thepump outlet without allowing the particles to pass through the pump, andconcurrently backwashing the filter element by pressurized fluid fromthe pump.

8 Claims, 4 Drawing Figures F EZ Flat V FLUIDS FLOW SYSTEM WITHSELF-FLUSIIING REVOLVING FILTER BACKGROUND OF THE INVENTION 1. Field ofthe Invention This invention relates to the art of protecting fluidshandling devices, such as pumps, from contaminants in the fluids handledby the devices, and specifically relates to the filtering art. Theinvention is particularly useful in aircraft fuel systems to protect themain engine fuel pump without requiring a reservoir to store trappedfuel contaminants.

2. Description of the Prior Art Filters for engine fuel systems areusually of the contaminant trapping or retention type. These filters areeither incorporated in the fuel system between the booster pump and themain fuel pump or between the main fuel pump and the control device forthe fluid feed to the engine. In high altitude flying jet craft, suchfilters not only become clogged with fuel contaminants, but also withice particles, thereby requiring bypassing of the filter when thepressure differential across the filter media becomes excessive due toclogging. Of course, bypassing of the filter exposes the downstreamcomponents to the contaminants in the fuel.

Backwashing of filters is also known in the prior art as, for example,in the Karl E. Britton US. Pat. No. 2,101,211, but only a small portionof the filtered fluid is used for the backwashing operation, and thewashed-out contaminants are either trapped and separated from thecounter-stream or returned to the pump, thus failing to protect the pumpand requiring piping, reservoirs and the like not desirable in aircraft.

SUMMARY OF THE INVENTION The present invention now provides a system,such as an aircraft fuel system, which will afford continuous protectionof equipment, such as aircraft fuel pumps, against detrimentalcontaminant particles, does not require reservoir space to store trappedcontaminants, does not require filter element replacements, andmaintains a constant pressure drop.

According to this invention a continuously revolving filter elementintersects the inlet and discharge passages of the fluids handlingequipment, such as a pump, to be protected. Contaminant particles in thefluid are diverted from the inlet to the outlet of the equipment beingprotected without allowing the particles to pass through the equipment.Because of the continuous rotation of the filter media, contaminantparticles are removed from the fluid entering the equipment, whileconcurrently these contaminant particles are reverse flow flushed fromthe filter media by fluid leaving the equipment.

The continuous revolving filter is preferably positioned between theboost stage and the high pressure gear pump stage of a jet engineaircraft fuel system. The filter unit is preferably driven by amechanical power take-off from the engine driven fuel pump. While onelocalized portion of the filter media is filtering out contaminants fromfluid flowing therethrough in one direction, another localized portionof the filter media is being backwashed by fluid flowing through themedia in the opposite direction, and at the same time the filter mediais being rotated so as to progressively advance contaminated containingportions to the backwashing area while feeding clean portions to thefiltering area.

It is then an object of this invention to provide a fluids handlingsystem which will protect apparatus in the system from contaminants inthe fluids without requiring storage areas for the contaminants orreplacement of filtering elements.

Another object of this invention is to provide a continuous revolvingfilter between the boost and high-pressure stage of an aircraft enginefuel system which will remove contaminants from fluid entering thehigh-pressure stage and then be freed of said contaminants by fluidleaving this high-pressure stage.

A specific object of this invention is to provide a continuous revolvingfilter in the inlet and discharge passages of a pump to divertcontaminant particles in fluid being fed to the pump to the fluiddischarged from the pump without allowing the particles to pass throughthe pump.

Another object of this invention is to provide a jet engine aircraftfuel system which temporarily removes contaminants from fuel to protectthe main fuel pump of the system, and then reintroduces the contaminantsback into the fuel downstream from the pump.

Other objects, features and advantages of this invention will beapparent from the following description of a certain preferredembodiment of the invention, taken in conjunction with the accompanyingdrawings, although variations and modifications may be effected withoutdeparting from the spirit and scope of the novel concepts of thedisclosure.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view of onefluid flow system of this invention showing the revolving filter of theinvention incorporated between the boost stage and high pressure gearstage of a jet engine fuel system;

FIG. 2 is a schematic view of one arrangement for driving the revolvingfilter of this invention in a fuel system such as is shown in FIG. 1;

FIG. 3 is a vertical cross-sectional view, with parts in elevation, of arevolving filter according to this invention; and

FIG. 4 is a transverse cross-sectional view of the filter taken alongthe line IV-IV of FIG, 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT In FIG. 1 the reference numeral10 indicates generally one possible arrangement of a fluids handlingsystem according to this invention. In the system 10 jet engine fuelfrom a tank 11 is fed to a pump indicated generally at 12 and having aboost stage 13 and a gear stage or high-pressure stage 14. Thecontinuous revolving filter 15 of this invention is interposed betweenthe boost stage 13 and the gear stage 14 of the pump 12, with the fuelflowing from the booststage 13 entering an inlet 16 on one side of thefilter device 15, flowing through the filter, and then to the gear stage14, from which it enters the outlet side 17 of the unit 15, which is onthe opposite side from the inlet 16. The fluid again flows through thefilter 15 in the opposite direction from its first pass, and then flowsto fuel flow control equipment 18, and from this to the jet engineburner nozzle, such as 19.

It will be clear from FIG. 1 that the revolving filter 15 separatescontaminants from fuel about to enter the gear stage 14 of the pump andthen reintroduces the filtered-out contaminants to the fuel leavingthisgear stage.

As shown in FIG. 2, the pump 12, including both the boost and gearstages thereof, is driven through a power take-off 20 from the jetengine (not shown), and the revolving filter 15, in

turn, is driven through a power take-off 21 from the gear stage 14. Thepower take-ofi 21 includes an external pinion gear 22 directly coupledto a driven gear of the gear pump stage 14 which, in turn, drives aninternal spur gear 23 coupled to a drive shaft 24 for the filter unit15.

As best shown in FIGS. 3 and 4, the revolving filter unit 15 has agenerally circular housing 25 composed of mating cupshaped halves 26 and27 secured together by bolts such as 28. The housing part 26 has acentral boss 28 with a closed end aligned with a central boss 29 in thehousing part 27 having an open end. The bosses 28 and 29 carry bearings30 which rotatably mount the drive shaft 24. The shaft is sealed by aseal 31 in the open end of the boss 29.

The shaft 24 has an enlarged central hub portion 32 on which is secureda rotating filter disk unit 33 which radiates from the shaft across thecentral portion of a circular chamber 34 provided by the housing 25. Thefilter disk unit 33, as shown, is built up from end plates 35, each witha circular band 36 of holes. Connecting these holes and serving to holdthe assembly together are upright tubular elements 38. These tubularelements contain filter media such as stacked wafers of screen. Thescreen wafers may be of progressively finer mesh from the inlet to theoutlet ends of the tubes 38 (top to bottom as viewed in FIG. 3). Theunit 33 is a cylindrical plate or drum with flat end faces and acircular periphery of less diameter than the housing 25 so as to fitfreely in the chamber 34. The end plates 35 of the unit 33 may becomposed of metal, rigid plastic, or the like, with the holes arrangedin a circular band 36 surrounding the central hub portion 33 and withinextends to a solid peripheral portion. The band of holes 36 is composedof successive circular rows of holes registering with the filter media37.

The housing half 26 has internally threaded out-tumed bosses 39 and 40on opposite sides of the central boss 28. The housing half 27 hassimilar out-turned internally threaded bosses 41 and 42, with the boss41 being aligned with the boss 39, and the boss 42 being aligned withthe boss 40.

Each housing half 26 and 27 has an inwardly-projecting cylindricalflange 43 aligned with each boss 39-40 and pro-.

jecting inwardly into closely spaced relation with the faces of thefilter disk 33. These flanges 43 are externally grooved and carry in thegrooves thereof an O-ring seal 44. Cylindrical rigid seal rings 45surround the flanges 43 and seal against the O-rings 44. Springs 46between the housing halves and these circular seals 45, such aswave-washer springs, urge the seals 45 against the faces or sides of thefilter disk 33.

The band of holes 36 through the filter disk 33 has a radial width equalto or less than the internal diameter of the seals 45 so that the sealswill extend beyond the rows of holes, as illustrated in FIG. 5.

The flanges 43 and the seals 45 cooperate to confine localized areas ofthe band of holes 36 with the inlet passage 16 and the outlet passage17, identified in FIG. 1. Thus, as shown in FIG. 3, the boss or nipple39 communicates with a circular zone inside of the flange 43, and fluidfrom this boss flows through this localized zone, through the holes 36registering with this zone, and then into a similar zone on the oppositeside of the filter disk which communicates with the boss or nipple 41.In a similar manner the boss or nipple 42 discharges into a localizedzone on the opposite side of the housing, which, in turn, communicateswith a localized ring of holes diametrically opposite the holesregistering with the inlet, and these holes, in turn, discharge throughthe nipple or boss 40.

In FIG. 4 the localized zone of holes 36 registering with the inlet 16,as identified at 47, while the localized zone of holes registering withthe outlet 17 is identified at 48.

It will, of course, be understood that as the filter disk 33 is drivenby the drive shaft 24, the filter holes 36 will successively registerwith the zones 47 and 48, and fluid flowing through the inlet 16 will befiltered, with the contaminants being retained by the filter material 38in the holes. Only clear, filtered fuel can then enter the gear stage 14of the pump.

The fuel exiting from the gear stage 17 of the pump then enters theoutlet passage 17 and flows back through the filter disk 33 in adirection opposite to the direction of the first pass through thefilter. This, of course, backwashes the filter material 38 and removesthe contaminants from the filter. The cleaned filter portions are thenreturned to the inlet 16.

From the above descriptions it should, therefore, be understood that thefilter disk 33 is continuously rotated to advance cleaned portions tothe inlet, and the contaminated portions are simultaneously backwashedor cleaned. All of the contaminants are reintroduced into the previouslyfiltered fluid, and the filter element will not become clogged and doesnot build up a back pressure through the filter. Since the filter disk33 rotates continuously, any slush or ice particles tending to form inthe system will be worked and broken up to prevent a clogging of theinlet. This working of the ice particles tends to melt them, and if anyparticles do reach the outlet of the filter, they are flushed from thefilter by the highly pressurized fuel from the gear stage of the pump.

I claim as my invention:

1. A fluid flow system having a single fluid flow path in whichcontaminants in the fluid are bypassed around a device in the systemwithout leaving the system comprising a fluid conduit having an inletand an outlet end, a device having an inlet communicating with the inletend of the conduit and an outlet communicating with the outlet end ofthe conduit, a filter unit having a housing with a first flow passage inthe conduit ahead of the inlet of said device and a second flow passagein the conduit beyond the outlet of said device, a rotating filterelement in said housing receiving therethrough in one direction fluidsflowing through said first passage of the housing to remove contaminantsfrom the fluids, and receiving in the opposite direction fluids flowingthrough said second passage of said housing to backwash the contaminantstherefrom, and means for rotating said rotatable filter unit in saidhousing to simultaneously expose clean filter areas to said first flowpassage and contaminated filter areas to said second flow passage.

2. A fuel system for engines which comprises an enginedriven pump havinga boost stage and a high-pressure gear pump stage, a single conduitmeans having an inlet end feeding fuel to said boost stage and an outletend receiving fuel from said gear pump stage, a filter unit having ahousing with a first flow path between the boost stage and gear pumpstage receiving fuel from the boost stage in one direction anddischarging fuel to the gear pump stage and a second through flow pathreceiving fuel in the opposite direction from the gear pump stage to theoutlet of the conduit a revolving filter element in said housing drivenby said gear pump stage, and said revolving filter element presentingclean filter areas to the fuel entering the gear pump stage andsimultaneously presenting contaminated areas to the discharge from saidgear pump stage for backwashing the filter element.

3. An engine fuel system having a single fuel flow path in whichcontaminants in the fuel are bypassed around a highpressure pump withoutleaving the flow path which comprises a booster pump having an inletreceiving fuel from a source and an outlet discharging the fuel at lowpressure, a gear pump having an inlet receiving low pressure fuel fromthe outlet of the booster pump and an outlet discharging high pressurefuel to the engine, a filter having a housing with a first through pathbetween the outlet of the booster pump and the inlet of the gear pumpand a second through path between the outlet of the gear pump and theengine, a filter disk rotatably mounted in said filter housing coupledto said gear pump for corotation to successively exposed localized areasthereof to the first flow path and then to the second flow path wherebycontaminants in the low pressure fuel from the booster pump are removedfrom the fuel entering the gear pump while the contaminants aresimultaneously backwashed from the filter disk by the high-pressure fuelfrom the gear pump to be reintroduced into the fuel to the enginewhereby the gear pump is protected from contaminants and no build-up ofcontaminants will occur.

4. The filter unit of claim 3 including a housing with inturnedcylindrical flanges on opposite sides of the filter unit and circularseals surrounding said flanges engaging the filter unit to confine theinlet and outlet areas.

5. A fluid flow system having a flow path in which contaminants in thefluid are bypassed around a pump in the system without leaving thesystem which comprises conduit means having an inlet end and an outletend, a first pump in said conduit means receiving fluid from said inletend, a second pump in said conduit means receiving fluid from said firstpump and discharging fluid to said outlet end, a revolving filter insaid conduit means having a first passage receiving fluid from saidfirst pump en route to said second pump and a second flow path receivingfluid from said second pump en route to said outlet, a rotating filterdisk in said filter means movable through said first and second flowpaths to filter out contaminants en route to the second pump and totransfer said contaminants to said second flow path for backwashing thecontaminants into the outlet with fluid from the second pump, and sealmeans in each of said flow paths acting on the filter disk to confinethe flow through the disk to the localized successive areas of the diskexposed to the flow paths.

6. The filter of claim 5 wherein the seals are rings urged againstopposite faces of the filter disk.

7. The filter of claim 5 wherein the filter disk is a composite assemblyof upright tubular elements containing filter media.

8. The filter disk of claim 7 wherein the filter media are 5 stackedscreen wafers having successively finer mesh from the inlet to theoutlet ends thereof.

1. A fluid flow system having a single fluid flow path in whichcontaminants in the fluid are bypassed around a device in the systemwithout leaving the system comprising a fluid conduit having an inletand an outlet end, a device having an inlet communicating with the inletend of the conduit and an outlet communicating with the outlet end ofthe conduit, a filter unit having a housing with a first flow passage inthe conduit ahead of the inlet of said device and a second flow passagein the conduit beyond the outlet of said device, a rotating filterelement in said housing receiving therethrough in one direction fluidsflowing through said first passage of the housing to remove contaminantsfrom the fluids, and receiving in the opposite direction fluids flowingthrough said second passage of said housing to backwash the contaminantstherefrom, and means for rotating said rotatable filter unit in saidhousing to simultaneously expose clean filter areas to said first flowpassage and contaminated filter areas to said second flow passage.
 2. Afuel system for engines which comprises an engine-driven pump having aboost stage and a high-pressure gear pump stage, a single conduit meanshaving an inlet end feeding fuel to said boost stage and an outlet endreceiving fuel from said gear pump stage, a filter unit having a housingwith a first flow path between the boost stage and gear pump stagereceiving fuel from the boost stage in one direction and dischargingfuel to the gear pump stage and a second through flow path receivingfuel in the opposite direction from the gear pump stage to the outlet ofthe conduit a revolving filter element in said housing driven by saidgear pump stage, and said revolving filter element presenting cleanfilter areas to the fuel entering the gear pump stage and simultaneouslypresenting contaminated areas to the discharge from said gear pump stagefor backwashing the filter element.
 3. An engine fuel system having asingle fuel flow path in which contaminants in the fuel are bypassedaround a high-pressure pump without leaving the flow path whichcomprises a booster pump having an inlet receiving fuel from a sourceand an outlet discharging the fuel at low pressure, a gear pump havingan inlet receiving low pressure fuel from the outlet of the booster pumpand an outlet discharging high pressure fuel to the engine, a filterhaving a housing with a first through path between the outlet of thebooster pump and the inlet of the gear pump and a second through pathbetween the outlet of the gear pump and the engine, a filter diskrotatably mounted in said filter housing coupled to said gear pump forcorotation to successively exposed Localized areas thereof to the firstflow path and then to the second flow path whereby contaminants in thelow pressure fuel from the booster pump are removed from the fuelentering the gear pump while the contaminants are simultaneouslybackwashed from the filter disk by the high-pressure fuel from the gearpump to be reintroduced into the fuel to the engine whereby the gearpump is protected from contaminants and no build-up of contaminants willoccur.
 4. The filter unit of claim 3 including a housing with inturnedcylindrical flanges on opposite sides of the filter unit and circularseals surrounding said flanges engaging the filter unit to confine theinlet and outlet areas.
 5. A fluid flow system having a flow path inwhich contaminants in the fluid are bypassed around a pump in the systemwithout leaving the system which comprises conduit means having an inletend and an outlet end, a first pump in said conduit means receivingfluid from said inlet end, a second pump in said conduit means receivingfluid from said first pump and discharging fluid to said outlet end, arevolving filter in said conduit means having a first passage receivingfluid from said first pump en route to said second pump and a secondflow path receiving fluid from said second pump en route to said outlet,a rotating filter disk in said filter means movable through said firstand second flow paths to filter out contaminants en route to the secondpump and to transfer said contaminants to said second flow path forbackwashing the contaminants into the outlet with fluid from the secondpump, and seal means in each of said flow paths acting on the filterdisk to confine the flow through the disk to the localized successiveareas of the disk exposed to the flow paths.
 6. The filter of claim 5wherein the seals are rings urged against opposite faces of the filterdisk.
 7. The filter of claim 5 wherein the filter disk is a compositeassembly of upright tubular elements containing filter media.
 8. Thefilter disk of claim 7 wherein the filter media are stacked screenwafers having successively finer mesh from the inlet to the outlet endsthereof.